Kobylewski & Jacobson. International Journal of Occupational and Environmental Health. 18(3): 220-246.
This review of the toxicology of food dyes finds that all nine of the currently approved dyes in the US have health concerns, including cancer, contamination with benzidine or other carcinogens, hyperactivity and hypersensitivity reactions.
Kobylewski believes that since the dyes do not improve the safety or nutritional quality of foods, they should all be removed from the food supply and replaced (if at all) by safer colorings.